The default setting is 45 degrees Celsius, but since the temp sensor isn’t calibrated it can be more than 10 degrees wrong. So be sure to set the thermal threshold to whatever tickles your fancy.
Right, max is I think 70º C and you can set it below that down to like 43º C (or I’ve seen it blink that out, anyway)
The thing to remember is that the sensor is in the driver itself, so there will be a delay. Try to set it just shy of where it’s uncomfortable to you and that should allow it some leeway. It’s gonna get pretty dang warm even on the lowest setting, but we control that by not using full Turbo level for very long at a time. It’s the wonderful thing (and the PITA) about ramping, you never really know where you are so it’s not as easy to monitor battery use or output as having 5 or 7 levels. The price to pay for the convenience of dimming control.
thank you for those replies on thermal config. I’m cool now.
I’ve set one of my D4:s as low as 35 degrees, which makes the light OK to use even for “mugglers”.
Mine throttles pretty fast and couldn’t burn anyone on the first turbo run, but if you fire it up in succession look out.
LMAO! Now that is humorous! 
:+1:
That looks almost perfect. It may even replace my BLF X6v2 for compact throw purposes. It looks like it’s about the size of a BLF X5 (14500 cell), but with a little more throw and a lot more power.
It should keep the light from hurting itself. I tried letting a 219c model run on maximum without thermal regulation for a couple minutes and even then the only damage was it made an O-ring get a bit flaccid. With thermal regulation on, it should keep itself far cooler than that. And it doesn’t have an option to turn that off unless you reflash the firmware.
However, that doesn’t mean it can be used with zero caution. People have already experienced some “nut roasting” due to turbo in a pants pocket. It can start fires. If left on maximum while wrapped in a blanket, it could theoretically still damage itself despite the thermal regulation — it could catch the blanket on fire before the driver even notices things are getting warm.
So be careful. But yes, during normal use, it shouldn’t damage itself.
That yellow spot sure does get obnoxious at times, no? I know it’s only a little thing, but with multiple colors in the beam it ends up looking bad no matter what the tint is.
Will be ready first the compact or bigger version of D1/D1S?
Crazy, isn’t it?
Yes, ish. The sensor isn’t calibrated, and it’s known to vary by as much as 12 C between different MCUs. So if it blinks 39 C, it really could be anywhere from like 30 C to 42 C. I biased the internal calibration to make it err on the safe side, so there’s more than a 50% chance that the actual temperature is lower than what it says.
That’s the thing about recovery. If you feel okay, like you could do more, that means you’re doing something right and should keep doing it — instead of pushing yourself.
It’s not unlike how the thermal regulation algorithm works. If you go too far, you have to cut back quite a bit until you start feeling better. Then move forward slowly, in baby steps. If you go too far again, it’ll likely involve big setbacks again, so try not to do that. 
Recovery goes a lot faster if you don’t keep hurting yourself.
This was mostly answered already, but the default is 45 C, the maximum is 70 C, and the minimum is 0 C.
I’d have to check again, but I think the only ways to reset it to default are:
- Manually calibrate it to 45 C (not easy to do).
- Manually calibrate it to something colder than freezing. IIRC, it detects this as “unconfigured” and resets to default.
The lowest calibration it’ll accept is 0 C. Anything below that wraps around to 255 C and starts counting down, which reads out as 0 C in temperature check mode or, if saved during calibration, triggers a reset to default. But the default doesn’t really matter since it’s only a rough approximation.
Based on ToyKeeper’s fantastic review, I received a Nichia 219 version today from Intn’Outdoor. Of course I just now ordered Vinh’s XPG2 version for its boosted lux. Both versions will be a lot of fun!
help please. When I do the thermal configuration, my light blinks 7 times. Is that 70 Celsius? If so , that is 158 Farenheight. What does that mean exactly please? Does that mean my light won’t step down until it becomes very, very , hot? If so, how do I get it back to the other end of the spectrum? Thanks anyone in the know.
You could use the timer function saypat, make sure light is cold to start and after the 10+ presses and hold, wait for it to blink out, then the short flicker. Keep hold whilst it sets off in turbo, as it gets warmer release the switch to set it. This will now be set more hand friendly…………….Of course double clicking when quite warm will still get it toasty!!! So i try and set mine from cold and find a happy medium regarding temp.
Yes, that’s probably 70. The zero digit should be a very short blink.
To set the thermal limit, turn the light off. Then click ten or more times and, without missing a beat, press and hold the button. Keep holding until the light feels hot, then let go.
While you’re holding it, it should blink out a number, then “buzz” for a few seconds, then go to turbo. Then it should stay at turbo until you let go. After you release the button, it should blink out a new number representing the new temperature ceiling value.
You have better replies above on changing the set point than I can provide so I won’t add to that confusion. I will say that you need to remember that the microcontroller is measuring the temperature of the driver and surrounding area inside the head, where the heat is highest, so the body of the light is not going to reach that temp. It will still get too hot to hold if you don’t pay attention, but don’t confuse the set point with the surface temperature.
Unless it’s been bored for a 20700 and has Nichia 219’s, then the surface temperature rockets past what the MCU is seeing and it’ll HOYT YA! 
My D4 is a bullriding champion, 9 seconds and you’re still holding on you win the blue ribbon! [FWIW, the MCU flashes out 53ºC]
?
I was running my light on turbo this morning and noticed that instead of gradually stepping down as normal, it blinked three times then stepped down quite a bit. I check battery V and it was reading 3.3 on an 18650GA.
Does anyone know what that means? It wasn’t running very hot at the time of blinking. I am guessing that it’s not able to get the juice it needs but would like someone to confirm.